The basic concept of using some type of hold-down unit for a truck or vehicle for securing a tie-down rope under tension about a load has been known in the past. A number of different types of units for this purpose, are disclosed in the following U.S. Pat. Nos.: 776,541; 3,090,559; 1,031,357; 3,426,996; 2,628,397; 3,848,889; 2,946,563.
None of the foregoing utilize a jacking unit which incrementally shifts the tie-down rope so that the tension is progressively applied to the rope. Such a jacking unit is easy to operate and is superior to the rotable type of hold-down devices shown in several of the above patents.
Attempts, however, have been made to use a jacking unit for this purpose. In such a case, the rope end attached to such a unit has been wound around a cleat secured to a movable bar coupled to the jacking unit itself. This requires a strong connection between the cleat and the bar and considerable time and expense is required to achieve this aim. Also, the rope, unless it is securely coupled to the cleat, has a tendency to slip, causing tension on the rope to decrease.
Because of the foregoing drawbacks, a need has arisen for an improved hold-down unit which eliminates the problems of this type of jacking unit and allows for a more positive hold-down capability yet without the sacrifice of tension on the tie-down rope.